Airbag module canister

ABSTRACT

An airbag module comprising an improved canister, retainer assembly and method of attaching the airbag module to the vehicle is disclosed. The canister includes snap-on end caps, which assemble onto the center section of the canister. A retention mechanism provides the snap-on capability, while a lap joint provides extra security to ensure the end caps remain on the center section during assembly and initiation of the inflator secured within the canister.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional PatentApplication Ser. No. 60/559,356 filed Apr. 2, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an inflatable passiverestraint airbag module for restraining the movement of a seatedoccupant in a vehicle during impact and, more particularly, to animprovement in the canister and retainer, the method of assembly, and tothe method for attaching the airbag module to the vehicle.

2. Description of Related Art

Safety restraint systems which self-activate without the need forintervention by an operator, i.e., “passive restraint systems,”typically are installed into a vehicle as an airbag module. The airbagmodule generally includes an inflatable cushion or airbag, an inflator,a canister, and a retainer to hold the airbag cushion and inflatorwithin the canister. The canister provides structural support duringinflation of the airbag and also provides a mounting base forinstallation of the airbag module in a vehicle. The canister istypically formed as an open mouth container with a center section andend plates fastened at each end by welds. During assembly of thecanister, multiple specialized jigs as well as skilled operators arerequired to align the end caps properly on the center section forwelding. If the end caps and center section are not aligned properly,the canister may not perform as desired during inflation because ofdeformation, thereby releasing the airbag or allowing gas leaks duringinflation and preventing the airbag from being properly inflated.Complicating the circumstance is the fact that there are many bracketsor fastening members welded to the center section to allow the airbagmodule to be secured within a vehicle. To provide the proper fit andfinish when the airbag module is assembled into the vehicle, thesefastening attachment members generally require special jigs and skilledoperators to properly place them on the canister. Each jig used toassemble the canister is expensive and is typically unique to aparticular canister and a particular vehicle, thus resulting in asignificant amount of lost set-up time if a switch between vehicles orcanisters is made.

Also typically used in airbag modules is a gas diffuser which diffusesthe gas from the inflator, secured in a lower part of the canister, intothe airbag, which is secured in the upper part of the canister. Thediffuser helps proper gas flow into the airbag to ensure the desiredinflation characteristics. The gas diffuser is typically secured to thecanister by a retainer which also secures the airbag to the canister.During inflation the airbag applies a significant amount of stress andforce to the canister and retainer and therefore each must be made outof a relatively thick sheet of metal which may limit tool life duringformation of the canister, retainer, and diffuser. The gas diffuser andretainer being separate items also require additional assembly time tobe properly assembled into the vehicle. The multiple attachment pointsthat must also be attached to the vehicle require significant assemblytime especially in aligning the canister for the proper fit and finish.The multiple fasteners and limited space available when the canister isassembled into the vehicle adds additional production steps and slowsthe assembly process, thereby increasing assembly cost.

Some manufacturers proposed snap tabs to assemble the end caps onto thecenter section of the canister. Typically these manufacturers usefastener assemblies such as bolts and nuts to ensure that the end capsare secured directly to the center section due to the stress experiencedduring deployment of the airbag. Other manufacturers proposed using theinflator which is bolted in place to further secure the end caps ontothe canister. However, this latter approach raises additional problems.For example, and given the wide range of tolerances for the inflator, itis difficult to ensure that the end caps are properly secured and thatthey are not too loose or too tight. Improperly secured end caps maycause additional stress which may affect the performance of the canisterduring deployment of the airbag. Further, these snap tab attachments maybe difficult to assemble properly with the proper alignment andgenerally do not perform during deployment of the airbag as well aswelded assemblies.

SUMMARY OF THE INVENTION

The present invention relates to inflatable passive restraint systems,and specifically relates to airbag modules that allow easier assemblyand greater strength. The present invention includes an airbag modulehaving an improved canister, retainer assembly and method of attachingthe airbag module to the vehicle.

The canister includes snap-on end caps, which assemble onto the centersection of the canister. A retention mechanism provides the snap-oncapability, while a lap joint provides extra security to ensure the endcaps remain on the center section during assembly and initiation of theinflator secured within the canister.

The retainer assembly is configured to allow the gas diffuser andretainer to be combined, thereby saving weight, improving assembly timesand allowing for a more compact airbag canister. The retainer assemblyalso works in conjunction with the canister to interlock the end capswith the center section using retainer studs.

Further scope of applicability of the present invention will becomeapparent from the following detailed description, claims, and drawings.However, it should be understood that the detailed description andspecific examples, while indicating preferred embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given here below, the appended claims, and theaccompanying drawings in which:

FIG. 1 is a perspective view of the airbag module coupled to a vehiclewith portions of the vehicle shown;

FIG. 2 is a partial side view of the airbag module coupled to a vehicle;

FIG. 3 is a sectional view of the airbag module shown in FIG. 2;

FIG. 4 is a perspective view of the airbag module showing the canister,retainer, and inflator;

FIG. 5 is a top view of the airbag module showing the canister,retainer, and mounting plate;

FIG. 6 is a perspective view of the canister;

FIG. 7 is an alternative perspective view of the canister;

FIG. 8 is a top view of the canister and the mounting member plate;

FIG. 9 is a bottom perspective view of the canister and mounting memberstuds;

FIG. 10 is an enlarged partial bottom perspective view showing thecanister with an end cap secured to the center section of the canister;

FIG. 11 is a bottom view of the canister;

FIG. 12 is a rear view of an end cap aligned for assembly onto thecenter section of the canister, partially illustrated;

FIG. 13 is a rear view with the end cap assembled onto the centersection of the canister, again partially illustrated;

FIG. 14 is a perspective view of the center section of the canister;

FIG. 15 is an enlarged partial top view of the canister showing the lapjoint and retention mechanism;

FIG. 16 is an enlarged outer perspective view of the lap joint andretention mechanism, partially shown;

FIG. 17 is an enlarged inside perspective view of the lap joint andretention mechanism, again partially shown;

FIG. 18 is a perspective view of the retainer assembly;

FIG. 19 is a perspective view of the mounting member assembly;

FIG. 20 is a perspective view of an alternate embodiment of the presentinvention showing the canister with integral end units; and

FIG. 21 is a bottom perspective view showing a plurality of retentiontabs and a like number of cavities for the alternative embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides an improved airbag module, generallyillustrated as 10, for use in inflatable passive restraint systems forrestraining the movement of a seated occupant in a vehicle during acollision. As illustrated in FIG. 1, the airbag module 10 is attached toa vehicle 12. As more clearly shown in FIG. 2, the airbag module 10 isattached to a vehicle mounting system 14. The airbag module 10 isillustrated as being a passenger airbag module although it should beunderstood that the invention also has applicability with other typesand kinds of vehicles and in other locations within a vehicle.

The airbag module 10 is generally a self-contained unit that includes acover 18, a canister 20, an inflator 24, and a cushion pack 25(illustrated in FIG. 3). The cushion pack 25 includes a retainerassembly 80 (that acts as a diffuser assembly) and a wrapped airbag 27.As illustrated in FIG. 2, the cover 18 is generally designed to provideclosure to the canister 20 thereby covering the airbag within thecanister and providing a smooth surface with the instrument panel 16.The airbag cover 18 is shown as being attached to the canister 20 with acover attachment mechanism 22 which allows for ease of assembly byallowing the cover to be attached and retained to the canister withoutfasteners. Other fastening mechanisms may be used to retain the cover 18to the canister 20.

The inflator 24 is generally elongated and cylindrical in shape. Theinflator 24 is attached to the canister 20 with an inflator fasteningsystem 26, as described below in greater detail. The inflator 24generally discharges gas from one end which is diffused by the retainerassembly 80 into the airbag during inflation, which in turn breaksthrough the cover 18 to provide a passive restraint system to a vehiclepassenger.

The canister 20 generally includes a center section 30, an inboard endcap 48, and an outboard end cap 50 and is adapted to house the inflator24, the airbag, and the retainer assembly 80, as illustrated in FIG. 4.In the illustrated embodiment, the canister 20, specifically the centersection 30 and end caps 48, 50, are fabricated of stamped steel,although it will be appreciated that various other metals such asaluminum or magnesium in stamped or cast forms and other polymericmaterials having light weight and high strength may be used.

The center section 30 has the general form of a long, narrow, openreceptacle or trough, although other configurations may readily be used.The center section 30 includes a portion of the retention mechanism 40for securing the end caps 48, 50 thereon, retention fastening holes 34,center interlock holes 32, a portion of the lap joint 28, or an edge ofthe plate portion, and a mounting member cavity 46. The center section30 may be made in a variety of sizes, shapes, and configurations to fita variety of vehicles. When assembled, the center section 30 isgenerally divided into two parts by the retainer assembly 80. In onepart the inflator 24 is retained and in the other part the airbag (notshown) is retained. The interlock holes 32, retention fastening holes34, lap joint 28, retention mechanism 40, and mounting member cavity 46will be described in greater detail below in conjunction with otherportions of the airbag module 10.

The end caps 48, 50 close the ends of the center section 30 and are alsogenerally formed from stamped steel. In order to permit the inflator 24to be inserted into the airbag module assembly 10 as a latter step oroperation of the assembly process, an inflator opening 52 is provided inthe end cap 50. The inflator opening 52 allows the inflator to beinserted after assembly. The opposing end cap 48 generally. includes aninflator fastener hole 54 through which a portion of the inflatorfastening system 26 extends. The inflator fastener hole 54 is generallysmaller than the inflator opening 52 and is configured to receive athreaded stud which may be secured by a nut placed on the stud.

An advantageous characteristic of the airbag module assembly 10 of thepresent invention is its adaptability to accommodate inflators ofdifferent lengths. The inflator 20 is fitted between the end caps 48,50. In the event that the use of a longer inflator than the illustratedinflator 20 is desired, the inboard end cap 48 which is illustrated asbeing deeply recessed can be interchanged with another inboard end cap(not shown) which is not as deeply recessed as is the illustrated endcap 48. While the end cap 48 is shown as being interchangeable toaccommodate a longer inflator it is to be understood that the outboardend cap 50 may be interchangeable instead of or in addition to theinboard end cap 48.

In accordance with one aspect of the invention, the end caps 48, 50 snapon the center section 30 for ease of assembly. The retention mechanism40 allows for ease of assembly by aligning the end caps 48, 50 properlyand providing a snap assembly. More specifically, at least one of thecenter section 30 and end caps 48, 50 includes retention tabs while theother of the end caps and center section includes retention cavities 44as illustrated in FIGS. 6 through 14. As may be seen in FIG. 7, avariety of these retention cavities 44 and retention tabs 42 lock theend cap on the center section where the end cap 50 overlaps the centersection 30. The number of retention tabs 42 and retention cavities 44may vary from embodiment to embodiment but generally include enoughretention tabs and cavities to ensure that the end caps 48, 50 remain onthe center section 30 during detonation of the inflator 24. Asillustrated in the figures, the retention tabs are simply a ramp stampedout of one of the center section 30 or end caps 48, 50 which force theend cap over the ramp until the retention tabs 42 fit within the cavity44. Retention tabs 42 include a retention edge 43 which engages thecavity wall 45 to prevent the end caps 48, 50 from being removed fromthe center section 30 once the end caps 48, 50 are installed onto thecenter section 30.

To further provide better alignment during assembly and increase theretention characteristics of the end caps 48, 50 on the center section30, a lap joint or edge 28 may also be provided. The lap joint 28generally includes a first joint member 36, or edge, on one of the endcaps 48, 50 or center section 30 and a second joint member 56 on theother of the center section and end cap. As illustrated in FIGS. 13 and15, the first joint member or edge 36 of the plate portion on the centersection 30 engages an opposing side of the end cap 50 as compared to theretention tabs 42. Therefore, when the end cap 50 is secured on thecenter section 30, the lap joint 28 increases the retention capabilityand helps ensure during inflation of the airbag that the end caps remainproperly on the center section. The first joint member 36 may alsoinclude a first joint alignment member 38 while the second joint member56 may include a second joint alignment member 58. As illustrated inFIG. 15, the first joint alignment member 38 is a ramp opposing theramps on the retention tabs 42. The second joint member 58 isillustrated on the end cap 50 as having an offset to place the secondjoint member 56 somewhat inside the center section so that the lap joint28 has the second joint member 56 secured inside of the first jointmember 36 on the center section 30, while the rest of the end cap 50 issecured around the outside of the center section. While the lap jointarrangement is shown and described in FIGS. 13 and 15 with respect tothe outboard end cap 50, it is to be understood that a similararrangement may be provided for with respect to the inboard end cap 48as shown in FIGS. 4 and 7.

The end caps 50 also include end cap interlock holes 60 that when theend caps 50 are properly assembled on the center section 30 align withthe center interlock holes 32.

The retainer assembly 80 generally includes the retainer studs 88, adiffuser cavity 86, and a flange 84. The retainer assembly 80 acts as aretainer for the airbag, a diffuser to diffuse gas into the airbag and astructural member to absorb stress. Through the flange 84, the retainerassembly 80 functions to increase the structural integrity of thecanister 20. The flange 84 also serves to fasten the retainer assembly80 to the canister 20. The flange 84 preferably extends around theperiphery of the retainer member to provide structural rigidity. Theretainer assembly 80 (specifically, the retainer studs 88) act as aninterlock to lock the end caps 48, 50 onto the center section 30.

In addition, the retainer assembly 80 (which is part of the cushion pack25) functions to attach the wrapped airbag 27 to the canister 20.Specifically, the airbag 27 includes an opening having a surroundingarea 85 (shown in FIG. 3). The opening communicates with the diffusercavity 86. A portion of the surrounding area 85 (shown in FIG. 3) iscaptured between the canister 20 and the retainer assembly 80. An arrayof holes is formed in the captured portion of the surrounding area 85through which pass the studs 88. The surrounding area 85 is thus lockedin place between the canister 20 and the retainer assembly 80.

A plurality of six retainer studs are illustrated although it is to beunderstood that a lesser or greater number of studs may be employed. Thenumber of studs used depends substantially on the output pressure of theselected airbag inflator. Specifically, as a general rule, the greaterthe output pressure of the inflator, the higher the number of studsrequired.

The diffuser cavity 86 is illustrated as a single cavity, but multiplediffuser cavities may be used to diffuse gas into the airbag in adesired manner. Some of the retainer studs 88 fit into the retainerfastener holes 34 on the center section 30 while other retainer studsact as interlocks to ensure the end caps 48, 50 are securely fastened tothe center section 30 and eliminate the potential for the end caps tobecome disassociated from a center section during inflation of theairbag. The retainer studs 88 that act as interlocks are insertedthrough both the center interlock holes 32 and end cap interlock holes60. By using the studs 88 to lock the end caps 48, 50 on the centersection 30 the retainer assembly 80, specifically the retainer cover 82,helps the canister absorb not only lateral forces but longitudinalforces experienced by the canister 20 thereby adding to the structuralintegrity to the canister. The retainer cover 82 uses the flange 84 tohelp absorb stresses during inflation of the airbag such as initiationof the inflator 24, the inflation of the airbag, and the stressesexperienced as the airbag completely fills. The retainer studs 88 alsoallow ease of assembly by further supporting the ability of the end caps48, 50 to lock onto the center section 30 without a fastener assembly todirectly fasten the end caps 48, 50 to the center section 30. Therefore,only the retainer assembly needs to be fastened to the canister 20.

Before the retainer assembly 80 is installed, typically a mountingmember assembly 70 is installed within the mounting member cavity 46.The mounting member 70 generally includes a mounting member plate 72 andmounting member studs 74. The mounting member cavity 46 formed on thecanister 20 may be configured in a variety of sizes and shapes andgenerally is configured to receive mounting member plate 72 whichsecures the canister 20 to the vehicle with the mounting member studs.The mounting member plate 72 is generally a steel plate slightly thickerthan the steel used to form the center section 20 to provide structuralrigidity to hold the canister and thereby the airbag module 10 in placewith only two mounting member studs 74. The mounting member studs 74 mayattach to the vehicle mounting system 14 as shown in FIG. 2. By usingonly a two-point attachment system, the present invention allows forease of assembly into the vehicle 12. Having recognized the use of themounting member assembly 70, it should be understood that according toan alternate embodiment of the present invention the studs may be fitteddirectly to the canister 20 without the necessity of a mounting memberplate.

In the first alternative embodiment, the canister 20′ is formed withintegral end units 100. More specifically, the canister 20′ is stampedwith the integral end units aligned with one of the walls of the centersection. The integral end units 100 are then folded along the fold line102 to be secured in a shape shown in FIGS. 20 and 21. The integral endunits 100 still snap in place although extra jigs may be required toproperly fold the units over into the final shape of the canister.

In all of the embodiments after assembly, if desired, the canister 20may be joined to the end caps 48, 50 or the integral end caps 100 to thecenter section 30. Joining may be accomplished by welding or by adeformation to both the end caps 48, 50 and the center section 30 by anymethod that would create an interlocking condition caused byinterference. By joining after assembly, expensive jigs and skilledoperators may be eliminated due to the canister 20 being alreadyassembled to proper tolerances before joining.

The combination of the retainer assembly 80 acting as an interlock tolock the end caps 48, 50 on the center section 30 provides for a strongcanister 20 for the airbag module 10 that is easy to assemble andsufficiently durable in use. The lap joint 28 and retention mechanism 40further allow for ease of assembly of the end caps 48, 50 onto thecenter section 30 and help retain the end caps 48, 50 on the centersection while the remaining portions of the airbag module are assembled.The combinations of all of the features described above of the presentinvention provide a sufficiently strong canister that in mostembodiments may be made out of a thinner steel than typically used forairbag canisters due to the strength and rigidity created by either themounting member assembly 70 or the retainer assembly 80 or a combinationof both the mounting member assembly and retainer assembly.

The foregoing discussion discloses and describes an exemplary embodimentof the present invention. One skilled in the art will readily recognizefrom such discussion, and from the accompanying drawings and claims thatvarious changes, modifications and variations can be made thereinwithout departing from the true spirit and fair scope of the inventionas defined by the following claims.

1. An airbag module for a vehicle, comprising: an inflator; an air baghaving an opening that is fluidly coupled to the inflator; a canisterthat is adapted to receive the inflator and the air bag, the canistercomprising: a center section, comprising: end portions provided onopposing ends of the center section; a cavity defined between the endportions; a center interlock hole placed at each of the end portions;end caps that are adapted to attach to corresponding end portions of thecenter section, the end caps comprising: a plate portion that is adaptedto couple to corresponding end portions of the center section to form areceptacle, the plate portion having a structure that receives andsecures the inflator; an edge that extends from the plate portion towardthe center section to engage corresponding end portions that areprovided on opposing ends of the center section; an end cap interlockhole that is placed at each of the end caps to align with the associatedcenter interlock hole placed at each of the end portions; and adiffuser, comprising: a retainer provided in the canister to define aspace between the center section and end caps for receiving theinflator; a flange provided along edges of the retainer that areproximate to the center section, wherein the flange is adapted tomechanically couple the air bag to the canister; a plurality of studsprovided in the flange to extend from the flange and to secure theretainer to the canister by penetrating through corresponding alignedones of the center interlock hole and the end cap interlock hole,wherein the plurality of studs fasten the end caps and the centersection to prevent disassociation of the end caps and the center sectionduring inflation of the air bag; and a diffuser cavity that is alignedwith the opening of the air bag.
 2. The airbag module of claim 1,wherein said center section and each said end cap includes a pluralityof apertures defined therein for receiving the studs.
 3. The airbagmodule of claim 1, wherein said inflator is substantially mounted withinsaid cavity that is defined by said center section, each said end cap,and said retainer assembly and wherein each said end cap isinterchangeable with another end cap to accommodate an inflator of adifferent length.
 4. The airbag module of claim 1, further including amounting member for attachment of the airbag module to the vehicle. 5.The airbag module of claim 4, wherein said center section has a recessdefined therein for receiving said mounting member.
 6. The airbag moduleof claim 5, wherein said mounting member has a stud for mounting theairbag module to the vehicle and wherein said center section has astud-passing aperture through which said stud is passed for connectionto the vehicle.
 7. The airbag module of claim 5, wherein said mountingmember includes two studs for mounting the airbag module to the vehicleand wherein said center section has two stud-passing apertures throughwhich said studs are passed for connection to the vehicle.
 8. The airbagmodule of claim 1, wherein said one of said center section or one ofsaid end caps includes a tab and the other of said center section orsaid end caps includes a tab-receiving slot, each said end cap beingfastened to said center section by the slotting of said tab into saidtab-receiving slot.
 9. The airbag module of claim 8, including aplurality of said tabs and a like plurality of said tab-receiving slots.10. the airbag module according to claim 1, further comprising a coverthat engages the canister to enclose the air bag within the canister.